Effects of bone morphogenetic protein-2 and transforming growth factor-β1 on gene expression of decorin and biglycan by cultured osteoblastic cells.

研究骨形态发生蛋白2（BMP-2）和转化生长因子β（TGF-β）对大鼠成骨细胞系ROS-C26（C26）小分子蛋白多糖、核心蛋白聚糖和双糖蛋白聚糖表达的影响。在存在或不存在rhBMP-2的情况下培养C26细胞3、6和9天后，与未用rhBMP-2处理的对照细胞相比，rhBMP-2处理的细胞中碱性磷酸酶活性增加，与它们分化成更成熟的成骨细胞成正比，而细胞中核心蛋白聚糖mRNA降低。这些结果在治疗后6天明显。然而，rhBMP-2处理对细胞中双糖蛋白聚糖mRNA表达没有影响。去除rhBMP-2后，加入不同浓度的TGF-β1（0、0. 1、1. 0、5. 0和10 ng/ml）培养24 h。TGF-β1剂量依赖性地降低细胞decorin mRNA的表达，但不影响其biglycan mRNA的表达。此外，从培养基中去除rhBMP-2或添加TGF-β1均显著降低rhBMP-2诱导的细胞的碱性磷酸酶活性。结果表明，成骨细胞分化伴随着碱性磷酸酶活性的增加和核心蛋白聚糖mRNA表达的减少，但双糖链蛋白聚糖mRNA的持续表达。rhBMP-2和TGF-β1均能抑制不同分化阶段成骨细胞核心蛋白聚糖mRNA的表达，但对双糖链蛋白聚糖mRNA和碱性磷酸酶的影响不同。

The influence of bone morphogenetic protein-2 (BMP-2) and transforming growth factor β (TGF-β) on the expression of small proteoglycans, decorin and biglycan was investigated in a clonal rat osteoblastic cell line, ROS-C26 (C26) cells, which is a potential osteoblast precursor cell line and capable of differentiating into mature osteoblasts after treatment with recombinant BMP-2 (rhBMP-2). Following the culture of C26 cells for 3, 6, and 9 days in the presence or absence of rhBMP-2, alkaline phosphatase activity increased in the rhBMP-2 treated cells in direct proportion to their differentiation into more mature osteoblastic cells, whereas decorin mRNA decreased in the cells, when compared to control cells without rhBMP-2 treatment. These results were evident 6 days after treatment. However, rhBMP-2 treatment had no effect on biglycan mRNA expression in the cells. Subsequently, after removal of rhBMP-2 from the culture media, the cells were further cultured for 24 h with graded concentrations of TGF-β1 (0,0.1,1.0, 5.0, and 10 ng/ml). TGF-β1 decreased decorin mRNA expression in the cells dose dependently, but did not effect their biglycan mRNA expression. Furthermore, either removal of rhBMP-2 from the culture media or addition of TGF-β1 significantly decreased alkaline phosphatase activity of rhBMP-2-induced cells. There results indicate that osteoblastic differentiation is accompanied by increased alkaline phosphatase activity and decreased expression of decorin mRNA, but continuous expression of biglycan mRNA. Both rhBMP-2 and TGF-β1 inhibit decorin mRNA expression in osteoblasts at varying stages of differentiation, but their effects on biglycan mRNA expression and alkaline phosphatase are different.